Impressed current protection of ships in fresh water

Abstract

A system for impressed current protection of a ship in fresh water has been investigated. A ship with dimensions of 38×17 m, which has spent two years on a river was observed. Impressed current protection was performed using two titanium anodes coated with 1 μm thick platinum. The basic external factors which influence corrosion have been studied. The natural potential of the corrosion of the ships hull was measured using a specially constructed Ag/AgCl electrode. The distribution of the potential along the ships hull was recorded, with a source voltage of 8.68 V. The necessary power and also all electrical parameters for an impressed current protection station were determined. The anode resistivity was determined from experimental measurements of electrical parameters in the system and with the voltage of 8.68 V. This value was also confirmed for the voltage of 18.0 V. Analytical and empirical methods for the calculation of anode resistivity with both real and measured values were compared. The results showed that significant differences exist.